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Identity HelpWhat is the locality of this Dioptase?

17th Aug 2019 21:31 BSTTama Higuchi

Hi everyone!  Amature collector here; I'm not experienced enough to know the localities of minerals just by looking at them, so I need your help!

I bought this Dioptase (on Calcite, I believe) a couple years ago, and since then I have irresponsibly misplaced the label, and I cannot remember what the locality for this specimen is.  

I know that most Dioptase come from Altyn-Tyube in Kazakhstan, Mindouli in Congo, and Tsumeb Mine or Kaokoveld in Namibia.  I compared this pictured Dioptase to my Altyn-Tube specimen, and the matrices look very different.  Because of that I'm leaning towards either the Congo or Namibia.  

If anyone has an idea, please let me know!  I understand that localities are difficult to figure out for sure, but I thought I'd ask a knowledgable community like you guys.

17th Aug 2019 21:45 BSTTama Higuchi

heres a closer look at the back of the specimen; I didn't really notice before, but there seems to be small yellow-green micro crystals on the matrix!

17th Aug 2019 22:29 BSTFrank K. Mazdab Manager

Are you sure you don't mean diopside?

17th Aug 2019 22:34 BSTTama Higuchi

Hi Frank!  Do you mean that the tiny green crystals could be diopside?  I guess it would make sense because of the color :-)

But the main crystal, the teal-colored ones coating the calcite, is definitely dioptase.

18th Aug 2019 00:51 BSTFrank K. Mazdab Manager

I guess my color vision is much worse than even I had always thought it was, because nothing in either photo has the shade of green I would associate with dioptase.

14th Sep 2019 07:51 BSTJolyon Ralph Founder

Looks like dioptase to me. Dioptase is notoriously difficult to photograph in the correct colour

17th Aug 2019 23:16 BSTErin Delventhal Manager

Certainly seems to me like several possible American localities for dioptase.

17th Aug 2019 23:20 BSTPaul Brandes Manager

In addition to many foreign localities as well, unfortunately.....

17th Aug 2019 23:22 BSTTama Higuchi

Perhaps Arizona?

18th Aug 2019 00:49 BSTMark Heintzelman Expert

Perhaps, but there's too many Dioptase localities in Arizona alone to ever reasonably assume it was from any one of them, let alone Arizona in general.  For something like this, retaining it's original label was absolutely critical.  Sorry about this.

18th Aug 2019 02:16 BSTHiro Inukai

In the second photo, about halfway down the image vertically, and 1/5th the width from the right-hand edge, there's a cluster of very tiny euhedral elongated crystals visible, but the magnification is not sufficient to provide stronger evidence of the species.  It does look like dioptase.  An image of this area of the specimen shot through a handheld 10x loupe may be enough for conclusive identification.

Note that many digitally captured images of dioptase give the appearance of the mineral as being more teal or blue than it appears to the human eye--this is well-documented as a photographic challenge (you can find the thread somewhere in the photography forum here).  So the color here is not in contradiction to the claimed species.  Moreover, it is also known that smaller/druzy crystals of dioptase can be very light in color.

That said, a precise locality is probably impossible to state.  Dioptase is relatively common and there are many localities worldwide, especially if the crystals are small as in this case.  The largest crystals are found in the more famous African mines around Tsumeb and Shinkolobwe, as well as the type locality Altyn-Tyube.  But given that these are such small crystals, in a way this almost excludes these localities as candidates.  Of course, that is not to say that the specimen is less interesting or aesthetic, since an example from a rare locality can be highly coveted, especially for collectors of this species.  (Fluorite, pyromorphite, and wulfenite are also examples of species that some collectors enjoy specializing in.)

18th Aug 2019 02:44 BSTTama Higuchi

I didn't even notice those little crystals on the right; they're quite beautiful.  I think I should invest in a loupe; I don't have one at the moment.

Also, excluding the African and Kazakhstani mines is helpful, I didn't consider how crystal size would factor into it! Looks like I need to do more research.

But as Mark said, figuring out the locality will be next to impossible.  Now, I am going to hunt like mad for the missing label, but I guess it will likely remain a mystery.

18th Aug 2019 02:54 BSTJeff Weissman Expert

Could be from the Christmas Mine in Arizona, especially if the clear crystals are apophyllite, otherwise, too many other possibilities.

18th Aug 2019 02:57 BSTTama Higuchi

Christmas Mine sounds vaguely familiar, but I don't want to trust my foggy memory in case I am remembering incorrectly.  If I ever find that darned label, I'll update ^^

18th Aug 2019 04:20 BSTMark Heintzelman Expert

As stated, too many possibilities. Dioptase is also associate with these truncated naillhead type calcite xtls at the Christmas mine, however the matrix of material I have with that association from there, is quite dissimilar to the specimen posted here.

18th Aug 2019 04:34 BSTDana Slaughter

Almost certainly the Christmas mine---I have collected here and the calcite crystals, as Mark mentioned, are distinctive for the mine. The matrix is also ok to me...looks like a bit of massive garnet. Very common association at this open pit mine.

18th Aug 2019 07:03 BSTAlfredo Petrov Manager

I agree with Dana re the Christmas mine being a likely candidate. Certainly not the type locality in Kazakhstan, nor Tsumeb.

18th Aug 2019 07:12 BSTCecil Cosse

I have a large dioptase from Morenci.  Does specimen have micro pyrite?  However, my piece does not have the calcite as your image shows.


18th Aug 2019 07:28 BSTTama Higuchi

Nope, no pyrite anywhere on mine!

18th Aug 2019 11:37 BSTPaul De Bondt Manager

No Congo either.

13th Sep 2019 20:24 BSTTama Higuchi

Just a quick update; I found the old listing from where I originally bought this specimen from, and turns out it is in fact from Christmas Mine, Arizona :-)  Thank you all for the help!
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